Method for forming reclosable access portals in film packaging

ABSTRACT

The present invention is directed to means for forming frangible, reclosable access portals in various types of film packaging, and specifically, to means for forming reclosable access portals that exhibit improved uniformity in the presentation of the access port beneficial for forming an effective reclosable seal, while substantially reducing the potential of deleterious tearing of the film packaging. The access port is formed from a region of the film packaging, which has been subjected to mechanical weakening of the film substrate, wherein the weakened regions include frangible, failure elements and force directing elements. Failure elements of the weakened region induce the film substrate to preferentially fail (i.e. tear) continuously in the general direction and bounds of the element.

TECHNICAL FIELD

[0001] The present invention is directed to means for forming frangible, reclosable access portals in various types of film packaging, and specifically, to means for forming reclosable access portals that exhibit improved uniformity in the presentation of the access port beneficial for forming an effective reclosable seal, while substantially reducing the potential of deleterious tearing of the film package.

BACKGROUND OF THE INVENTION

[0002] The use of film packaging is well known in the art as a means for sealing a product within a controlled environment and to prevent detrimental contamination. Products that have benefitted from such packaging include food products, tobacco, photographic film, medical aids, personal hygiene materials and home care agents. Of particular note, those products that are pre-moistened require an effective combination of durable film packaging with a strong, hermetic seal. The seal is not only a protective measure, but also, the unbroken seal indicates to the consumer that the package has not been improperly handled.

[0003] Typical retail availability of products ensconced in durable film packaging includes having packages that contain more than one such product, or plural elements, such as sheets, of the same product. In situations where the product is adversely affected by continued exposure to the environment, it is necessary in such plural element packaging that a seal can be reformed in the packaging after the initial element is removed, and that such seal be sufficiently effective to maintain the quality of the remaining elements until the last element is removed and the now empty packaging discarded.

[0004] A retail film package must be able to resist mechanical failure and contamination during shipping and handling, and yet be accessible to the common user. Forming frangible access portals in film packaging that are receptive to reclosable actions are complex due to the necessary combination of a durable film package and a strong, hermetic seal. Various prior art attempts have been made to form suitable closure means that do not compromise the ability of the film package to perform, including the use of molded thermoplastic closures and replaceable adhesive tabs. Molded thermoplastic closures allow for positive sealing action, but require additional forming steps. Further such thermoplastic closures require affixing to the film packaging, wherein such joining is in itself durable and leak-proof, and can form alternate paths of contamination including introduction of adhesives into the sealed environment within the film package.

[0005] Replaceable adhesive tabs require the formation of an access way into the interior of the sealed film package. Typical practices for forming such access ways include perforating or otherwise pre-cutting and preferentially weakening regions in the film face. The frangible pre-cut region is then forced open by the consumer by tearing of the film face, a process which has been found to be a very difficult to perform not only completely, but also in such a way as to prevent over-extension or miss-direction of the tearing force that results in a subsequent failure of the reclosable mechanism. Such over-extension failures are particularly evident when oriented films are used as one or more layers in the film substrate, with tearing tending to propagate in the direction of film orientation.

[0006] An unmet need exists for a method of forming reclosable access portals in film packaging that maintains the sealed environment during shipping and handling, and yet can be readily utilized by the common consumer, and which substantially reduces the potential of deleterious tearing or over-extension of the access way.

SUMMARY OF THE INVENTION

[0007] The present invention is directed to means for forming frangible, reclosable access portals in various types of film packaging, and specifically, to means for forming reclosable access portals that exhibit improved uniformity in the presentation of the access port beneficial for forming an effective reclosable seal, while substantially reducing the potential of deleterious tearing of the film packaging. The access port is formed from a region of the film packaging, which has been subjected to mechanical weakening of the film substrate, wherein the weakened regions include frangible, failure elements and force directing elements. Failure elements of the weakened region induce the film substrate to preferentially fail (i.e. tear) continuously in the general direction and bounds of the element. Representative failure elements include complete depth perforations, partial depth perforations, scoring, and embossed or otherwise thinned film substrate areas. Force directing elements are discontinuities in the failure element that redirect the force vector in a direction of at least 10 degrees from the continuous path, generally defined by the failure elements. By combining failure elements and force directing elements in the region of the access port, the film can be induced to fail in a controlled and reproducible way, thus allowing for improved re-closure performance.

[0008] The film packaging may comprise any suitable homogenous or heterogeneous substrate, optionally of either laminate or composite construction, which is compatible with the intended product to be so contained. The film substrate may include barrier performance agents such as fatty acids, as well as topically applied aesthetic modifiers such as colorants and printed inks.

[0009] It is presently envisioned that any profile of access portals can be practiced in accordance with the present invention, including, but not limited to; slits, ellipses, rectangles, and the combinations thereof, in which there is a combination of failure elements and force directors are combined in a discontinuous failure zone.

[0010] By application of the present invention, film packaging can be produced which forms uniform and reproducible access portals. It is within the purview of the invention that food materials, as well as hygienic, medical and home care products, can be packaged in suitable film substrates, wherein the clearly formed access portal allows for effective reclosable access.

DETAILED DESCRIPTION OF THE FIGURES

[0011]FIG. 1 is a photograph of a typical retail product as packed in a film package with a conventional unopened access port;

[0012]FIG. 2 is a photograph of an oval knife as is conventionally practiced in the formation of prior art access portals in retail film packaging;

[0013]FIG. 3 is a photograph of a retail film package wherein the access port has been formed utilizing the oval knife of FIG. 2;

[0014]FIG. 4 is a photograph of a modified knife having failure elements and force directing elements in accordance with the present invention; and

[0015]FIG. 5 is a photograph of a retail film package wherein the access port has been formed by way of the interaction of the failure elements and force directing elements.

DETAILED DESCRIPTION

[0016] While the present invention is susceptible of embodiment in various forms, there will hereinafter be described, presently preferred embodiments, with the understanding that the present disclosure is to be considered as an exemplification of the invention, and is not intended to limit the invention to the specific embodiments disclosed herein.

[0017] The present invention is directed to a means for forming frangible access portals in weakened regions of film packaging, which entails the combination of failure elements and force directing elements. Failure elements of the weakened region induce the film substrate to preferentially fail (i.e. tear) continuously in the general direction and bounds of the element. Representative failure elements include complete depth perforations, partial depth perforations, suitable scoring, and embossed or otherwise thinned film substrate areas. Force directing elements are discontinuities in the failure element that redirect the force vector in a direction of at least 10 degrees from the continuous path.

[0018] The failure elements enable the film to be torn by inducing a localized weakness in the film substrate. As force is applied to the failure elements, a tear is initiated in the film substrate, a tear which then propagates in the general direction and orientation of the failure element through continued application of force. At selected points along the failure element, wherein the incident angle of the failure element deviates by at least 10 degrees, force directing elements are introduced. Force directing elements terminate the propagation of the failure in the film substrate and allow for the force vector to be redirected from the continuous path. Such restraint of the tear prevents over-extension of the access portal beyond a predefined area in the face of the film packaging. Further, the force vector can be reoriented so as to initiate a new failure in the film substrate that is in a direction at least 10 degrees off of the path of the previous failure element. Such re-direction failure in the film substrate for forming an access opening therein can e particularly desirable in the case of oriented film substrates, where it can be desirable to form an opening which extends at least partially traversely to the direction of film orientation.

[0019] Suitable means for introducing failure elements and force directing elements into film substrates for packaging include the application of mechanical disruption of the film substrate, such as by application of metal knives, laser ablation, roll embossing, and hydraulic energy. The most preferred mechanism for inducing a frangible weakened region is through the use of metal knives that are forced against the film substrate. When metal knives are used, such as when presented as a cutting surface asperity in a section of tool steel, on a film substrate, the pressure and temperature of the process can be modulated simultaneously to obtain optimum cutting performance.

EXAMPLES

[0020]FIG. 1 depicts a representative product, which has been ensconced within film packaging. This particular product does not include any access portals as a way to obtain material from within the confines of the packaging. FIG. 2 is a sample of a cutting knife as has been practiced in the prior art, represented by U.S. Pat. No. 5,379,897, incorporated herein by reference. The knife-edge is presented as an elliptical surface asperity projecting out of the face of the tool steel base, which in turn, defines a failure element that extends continuously about the weakened region. When the prior art cutting knife is used to form a weakened region in the surface of the representative product, and force is subsequently applied to the region so as to form an access way, tears propagate beyond the boundaries defined by the cutting knife, as shown in FIG. 3.

[0021]FIG. 4 provides a representative cutting knife embodying the teachings of the present invention. The elliptical failure element includes two force directing elements, 2 and 3. The force directing elements are at least 10 degrees off of the incident angle defined by the failure element; in the illustrated embodiment, the force direct elements are oriented at approximately 90 degrees to the direction of tearing defined by the otherwise elliptical failure element. When the cutting knife of FIG. 4 is used to form a weakened region in the surface of the representative product, and force is applied, the tears propagate in the region specifically defined by the conjoined failure elements and force directing elements, and do not extend beyond the boundaries. Element 1 illustrated in FIG. 4 facilitates complete formation of the access opening, and forms a connector joining the separated portion to the remainder of the substrate.

[0022] From the foregoing, numerous modifications and variations can be effected without departing from the true spirit and scope of the novel concept of the present invention. It is to be understood that no limitation with respect to the specific embodiments disclosed herein is intended or should be inferred. The disclosure is intended to cover, by the appended claims, all such modifications as fall within the scope of the claims. 

What is claimed is:
 1. A method for forming access portals in film packaging, comprising the steps of: a. providing a film substrate, b. providing a means for imparting a weakened region in the film substrate, wherein said weakened region includes at least one failure element and at least one force directing element, and c. inducing said weakened region into said film substrate wherein said force directing element deviate from the failure element by an incident angle of at least 10 degrees as defined by the failure element.
 2. A method for forming access portals as in claim 1, wherein said film substrate is of heterogeneous formation.
 3. A method for forming access portals as in claim 1, wherein said means for imparting a weakened region are selected from the group consisting of mechanical knives, laser ablation, roll embossing, hydraulic energy, and the combinations thereof.
 4. A method for forming access portals in film packaging as in claim 1, wherein said failure elements are formed from full-depth perforations.
 5. A film package for products comprising of a film substrate, wherein said film substrate comprises at least one access portal, said access portal formed in the surface of the film substrate so as to create a weakened region, said weakened region including at least one failure element and at least one force directing element, wherein said force directing element deviates from the failure element by an incident angle of at least 10 degrees as defined by the failure element. 